| OBJECTIVE:Acute respiratory distress syndrome(ARDS)has high mortality and great harm.Prone position ventilation(PPV)can improve the prognosis of ARDS patients and is one of the important means of lung protective ventilation.Prolonged prone position ventilation may further improve the prognosis of patients,but the compression of the anterior chest wall and abdomen during PPV may also lead to respiratory restriction and carbon dioxide retention.Patients may have difficulty breathing and irritability,and long-term PPV often requires the combined use of sedatives,analgesics and even NMBAs.These factors may cause excessive inhibition of the patient’s respiratory muscles and affect the recovery of spontaneous breathing function.The above factors require us to carry out systematic,comprehensive and continuous respiratory mechanics monitoring for patients with moderate to severe ARDS who receive longterm prone position ventilation,so as to explore the dynamic changes of respiratory drive and mechanics in ARDS patients accepting PPV,and provide some reference for the adjustment of respiratory support parameters and the use of NMBAs in ARDS patients under prone position ventilation.METHODS:The study is a single-center prospective cohort study that included 22 ARDS patients admitted to the Department of Critical Care Medicine of the First Affiliated Hospital of Guangzhou Medical University from June 2017 to July 2022.The oxygenation index of these patients was less than 150mmHg(PaO2/FiO2,PFR ≤150mmHg)when they were transferred to the intensive care unit and met the 2012 version of Berlin criteria for the diagnosis of ARDS.The patients above were established artificial airway and received mechanical ventilation within 36 hours of being diagnosed with ARDS.After confirming that the patient’s hemodynamics was stable(mean arterial pressure>65mmHg,heart rate<120 beats/min,norepinephrine pumping injection speed<0.4μg/kg/min or dopamine pumping injection speed<10μg/kg/min)and there was no prone position ventilation-related contraindications the prone position ventilation treatment was performed on these patients with each time lasting no less than 12 hours.The respiratory mechanics data including esophageal pressure(Pes),esophageal pressure swings(ΔPes),inspiratory transpulmonary pressure(PLei),driving pressure(DP),transpulmonary driving pressure(DPL)were collected with an integrated four-channel multifunctional gastric tube and recorded by Labchart Data Analysing software during the supine position ventilation stage,early stage of prone position(the patients accepted PPV within 4 hours)and middle/late stage of prone position(the patients accepted PPV more than 12 hours).After collecting the respiratory mechanics data,the generalized estimating equations(GEE)of linear regression were used to perform stratified analysis according to the patient’s position,prognosis outcome(survival/death),and neuromuscular blocking agents using.RESULTS:(1)During the transition from supine position to prone position,the arterial oxygen partial pressure of patients increased significantly[PaO2(mmHg):SPV vs early PPV vs middle-late PPV:95.35 vs 109.46 vs 106.96,PSPV vs early PPV and PSPV vs middle-late PPV<0.05].At the same time,the oxygenation index of the patients was also significantly increased[PFR(mmHg):SPV vs early PPV vs middle-late PPV:147.86 vs 171.56 vs 169.78,PSPV vs early PPV and PSPV vs middle-late PPV<0.05].Esophageal pressure swings(ΔPes)were significantly higher in patients in middle-late PPV[ΔPes(cmH2O):SPV vs middle-late PPV:7.46 vs 8.30,PSPV vsmiddle-late PPV<0.05].(2)Stratified analysis according to the prognosis of patients shows that Peak airway pressure(Ppeak),esophageal pressure swing(ΔPes)and respiration rate(RR)were higher in the death group[Ppeak(cmH2O):death group vs survival group:27.48 vs 24.23,P death group vs survival group<0.05][ΔPes(cmH2O).death group vs survival group:8.95 vs 6.97,P death group vs survival group<0.01][RR(breaths/min):death group vs survival group:30.33 vs 23.34,P death group vs survival group<0.001].(3)Stratified analysis based on whether patients were treated with NMBAs showed that after using muscle relaxants Esophageal pressure swing(ΔPes),inspiratory transpulmonary pressure(PLei),transpulmonary driving pressure(DPL)and driving pressure(DP)were significantly decreased[ΔPes(cmH2O):NMBAs group vs non-NMBAs group:7.08 vs 8.76,P<0.01][PLei(cmH2O):NMBAs group vs non-NMBAs group:19.71 vs 24.69,P<0.001][DPL(cmH2I):NMBAs group vs non-NMBAs group:14.82 vs 18.08,P<0.001][DP(cmH2O):NMBAs group vs non-NMBAs group:16.73 vs 17.56,P<0.05].CONCLUSION:(1)During the prone position ventilation,the patient’s oxygenation was significantly improved.At the same time,under the condition of prone position ventilation,the patient’s esophageal pressure swing value increased obviously,but it not beyonded the normal range.(2)In the death group,the airway peak pressure,esophageal pressure swing value and respiratory rate were higher,and the difference was statistically significant.(3)The transpulmonary pressure,driving pressure and transpulmonary driving pressure during inspiratory period were significantly decreased in the patients treated with NMBAs.It may shows that the combination of prone position ventilation and NMBAs will be able to create co-lung protective effect in these patients. |
